When I connect the wires the screen lights up and comes on just fine. When I use the system the thermostat continually clicks on and so does the furnace. I checked the website of the thermostat and it said I need to use a common wire for a gas furnace. I traced the wiring to a honeywell aquastat relay. Mechanical Aquastat Wiring Diagrams Common wiring diagrams are shown below. Alternating On and [Setpoint] is displayed during a heating cycle while the circulator pump contacts are closed. shall be protected by metal conduit. NOTE: Line-voltage and safety-circuit wiring which is external to the water heater jacket when all panels are in place.. May 12, 2014 · Honeywell Type L8148A Aquastat Relay help I use one of these controllers for an oil fired hydronic system very basic. On a call for heat from one of my zone valves, zone valve opens-ok; circulating pumps should run-it does not. if you can post your wiring diagram, probably it's easy to figure out where the issue could be. 01-03-2010, 12:47.